docstr: Test for pickling of classical explainer
  :return:
docstr_tok: ["Test","for","pickling","of","classical","explainer",":","return",":"]
code: def test_pickle(self, tmpdir):
      """
      Test for pickling of classical explainer
      :return:
      """
      X_train, X_test, y_train, y_test = setup_mnli_test_train_split()
      label_encoder = LabelEncoder()
      y_train = label_encoder.fit_transform(y_train)
      explainer = ClassicalTextExplainer()
      classifier, best_params = explainer.fit(X_train, y_train)
      explainer_file_name = "explainer.pkl"
      explainer_file_path = tmpdir.mkdir("explainers").join(
          explainer_file_name
      )
      with open(explainer_file_path, "wb") as explainer_save_file:
          pickle.dump(explainer, explainer_save_file)
      with open(explainer_file_path, "rb") as explainer_load_file:
          explainer = pickle.load(explainer_load_file)
      os.remove(explainer_file_path)
      explainer.preprocessor.labelEncoder = label_encoder
      local_explanation = explainer.explain_local(DOCUMENT)
      assert len(local_explanation.local_importance_values) == len(
          local_explanation.features
      )
  
file_path: interpret-text/test/unit/test_classical_explainer.py
imports: from interpret_text.experimental.classical import ClassicalTextExplainer
  from sklearn.preprocessing import LabelEncoder
  from utils_test import setup_mnli_test_train_split
  import pickle
  import os
label_desc: Use image node_id 4 for calling the TestClassicalExplainer obj's underlying member method code with example usage: obj.test_pickle(tmpdir) without return types